I will survive

From Joe, age 38Dear Carole, I am a 38-year-old single gay man who is perfectly at ease with his sexuality, but I have this nagging feeling that I should be making an effort to perpetuate my genes. If I die without leaving any offspring surely I will have failed as a biological entity. I don't believe in life after death, so it will be as if I never existed.

Should I impregnate a friendly lesbian, or would it be simpler – and more efficient in evolutionary terms – to register as a sperm donor?

Carole replies:Do you have any nephews or nieces? It has been theorised that homosexuality, which remains at a stable level in human populations of around 4% for men and 2% for women, survives from generation to generation due to a phenomenon known as kin selection. This is the evolution of behaviours that favour the reproductive success of genetic relatives and has been observed in many species, us included.

Nephews and nieces share 25% of their genes with their aunts and uncles. The quarter of your genes you have in common with your sibling's offspring is second only to the half of your genes you would have in common with your own children. Thus, gay, lesbian or childless heterosexuals can increase their own reproductive fitness by behaving altruistically towards their nieces and nephews – in other words by helping to ensure their survival and future reproductive success.

There are many examples of kin selection in nature. Our New World primate cousin, the endangered golden lion tamarin, is a highly cooperative breeder. Pairs of males (sometimes brothers) both mate with the same female. When the infant is born neither male knows which is the father, and yet both invest equal care in the progeny. The more carers an infant tamarin monkey has the better its chances of survival.

Humans are no different in this regard. For example, a child born as the result of an alliance between a gay couple and a lesbian couple has two genetic parents and two "alloparents". With four adult carers this infant is better placed to succeed in the game of life than a child born to a heterosexual pairing.

In answer to the second part of your question: yes, as a sperm donor you could fulfil your fitness potential, potentially fathering several children (assuming women chose your sample – would you declare your sexuality when donating?). And so long as any resulting progeny do not try to find you later in life, you would have done so without incurring the potentially heavy costs of parenthood. Those costs would be met by sperm recipient and her partner.

Crime and punishment

From Nicholas, no age givenDear Carole, When I am coaching my football team, how can I best motivate them? Specifically, if somebody is late for training should I, a) punish that player, b) punish everybody, or c) not punish anybody, or d) something else? What if a player commits a foul in an actual game, should I punish them for that too?

Carole replies:A successful coach needs to be an alpha male, the team is your troop and to survive intact they must cooperate with one another and obey the rules and strategies you teach. To punish them all will lead to dissension in the ranks. Can you risk this? It would also mean punishing the late player twice over due to the resentment of the other players.

You ask whether you should punish a foul. The answer may depend on whether the foul leads to a goal, or to a penalty and the other team scoring. Many humans are Machiavellian, so their double standards will mean they silently overlook a foul that brings benefit, but raise the alarm over the ones that cause damage.

You mention, "d) something else" – one novel approach is called "spite", in which you punish yourself and "cut off your nose to spite your face". If you were a highly respected coach and had a bad leg, for example, you could make the punishment a physical exercise that obviously pains you. Your team would be distressed to see you suffer and would resent the tardy player. You might hope his guilt would make his timekeeping better (Kevin Costner attempts this strategy in The Guardian).

But a spiteful strategy frequently backfires. If you are not a highly respected and loved coach your team might think you an idiot for making yourself suffer. Your status could fall and your team's faith in your leadership evaporate. Your captain might challenge your authority, even ousting you and assuming the alpha role, at least temporarily, while a new coach is found. In fact, a lack of respect for the alpha may have contributed to the original tardiness.

Strategy "a)" may be the best option. Status is a great motivator (as are money and sex). Pull rank, punish the player for lateness and make his status fall.

As you break your dilemma down into game theoretic options I'm guessing you already have the answers you seek. But let's be honest, solutions found in textbook theories are not always applicable to real-life situations. There are always exceptions to rules, because the social realm is invariably complex.

For example, the player in question may be the most gifted in the squad, and a club further up the league table would love a chance to poach him. Perhaps he was late for training because on his way he took time to help a blind stranger across a busy road. With this additional information is option "a" still your best course of action?

The systematic punishments found written in dusty, draconian rulebooks are frequently unjust. Listening to and empathising with your players will help you accommodate all these social intricacies.